1989 Jaguar XJ6

XJ6
Ignition pulses are applied from a separate ignition amplifier to the ignition coil. The ignition coil generates high energy pulses for spark plugs. The distributor does not have a centrifugal or vacuum advance mechanisms. The distributor is only necessary to distribute spark to the proper cylinder.
Depending on engine speed and supply voltage, the dwell angle is changed and ignition voltage (energy) is adapted to that very instant. This prevents unnecessary energy consumption by the ignition coil. This also prevents peak coil current from flowing through the coil below a specific engine speed, preventing the battery from being discharged and ignition coil from overheating.

Using a spark tester check you are getting power from coil to distributor. IGNITION TIMING (XJ6)
ECU uses information supplied by airflow meter and crankshaft sensor to electronically control ignition timing.

Ensure engine is not misfiring. If necessary, check crankshaft position sensor, timing ring, and sensor air gap. Check voltage at mass airflow sensor pin No. 1 or 2 (zero volts) and pin No. 5 (12 volts).
Check mass airflow sensor output voltage. For specifications, see appropriate article in this section:
For XJ6, see ADJUSTMENTS.